At the time that printing came onto the scene in western Europe in the mid-1400s, the medical community was struggling in the depths of superstition, and little rational medicine was being practiced. With this new invention, a flood of ancient, outmoded texts was released upon the public, and eager readers frequently were unaware that books they were being sold as new works were actually in some cases a thousand years old. Added to this was the fact that the appearance in print of this irrational material lent credibility and authoritativeness to unscientific writings. Thus, in contrast to many other fields which were immeasurably helped by the advent of the printed book, rational medicine was in fact held back and prevented from developing for at least a full century. It was not until the Renaissance was well under way that important original contributions by such towering figures as Vesalius supplanted these worthless repetitions of ancient superstitions.